Gabriela is 16 years older than Ben. Sixteen years ago, Gabriela was 3 times older than Ben. How old is Gabriela now?
Explanation: We can use the given information to write down two equations that describe the ages of Gabriela and Ben. Let Gabriela's current age be $g$ and Ben's current age be $b$ The information in the first sentence can be expressed in the following equation: $g = b + 16$ Sixteen years ago, Gabriela was $g - 16$ years old, and Ben was $b - 16$ years old. The information in the second sentence can be expressed in the following equation: $g - 16 = 3(b - 16)$ Now we have two independent equations, and we can solve for our two unknowns. Because we are looking for $g$ , it might be easiest to solve our first equation for $b$ and substitute it into our second equation. Solving our first equation for $b$ , we get: $b = g - 16$ . Substituting this into our second equation, we get the equation: $g - 16 = 3($ $(g - 16)$ $ -$ $ 16)$ which combines the information about $g$ from both of our original equations. Simplifying the right side of this equation, we get: $g - 16 = 3g - 96$ Solving for $g$ , we get: $2 g = 80$ $g = 40$.